How to count property different values in json object

Question

I am getting a json objects from database. What is the Best practice to count number of ClassDef values A , B , C.
In the json object for eg: I have in this json " 2 A and 2 B and 3 c "

My json object:

[{
    "ItemCode": "200500303800356",
    "LastCost": 8,
    "OnHand": 593889,
    "InventoryValue": 4751112,
    "PercOfTotalInventory": 18.294517,
    "CumerativePercTotal": 18.29,
    "ClassDef": "A"
}, {
    "ItemCode": "201600701800197",
    "LastCost": 400,
    "OnHand": 300,
    "InventoryValue": 120000,
    "PercOfTotalInventory": 0.462069,
    "CumerativePercTotal": 75.68,
    "ClassDef": "A"
}, {
    "ItemCode": "200701507000107",
    "LastCost": 75,
    "OnHand": 239,
    "InventoryValue": 17925,
    "PercOfTotalInventory": 0.069022,
    "CumerativePercTotal": 91.75,
    "ClassDef": "B"
}, {
    "ItemCode": "200501303400308",
    "LastCost": 3515,
    "OnHand": 5,
    "InventoryValue": 17575,
    "PercOfTotalInventory": 0.067674,
    "CumerativePercTotal": 91.81,
    "ClassDef": "B"
}, {
    "ItemCode": "200200106701035",
    "LastCost": 80,
    "OnHand": 27,
    "InventoryValue": 2160,
    "PercOfTotalInventory": 0.008317,
    "CumerativePercTotal": 99.28,
    "ClassDef": "C"
}, {
    "ItemCode": "200200902700248",
    "LastCost": 10,
    "OnHand": 213,
    "InventoryValue": 2130,
    "PercOfTotalInventory": 0.008202,
    "CumerativePercTotal": 99.29,
    "ClassDef": "C"
}, {
    "ItemCode": "200601302001093",
    "LastCost": 0.3,
    "OnHand": 6,
    "InventoryValue": 1.8,
    "PercOfTotalInventory": 0.000007,
    "CumerativePercTotal": 100,
    "ClassDef": "C"
}]

Does any have an idea how to do this?

which value do you loke to count? just how many occurences or a special value? — Nina Scholz, May 18 '17 at 08:34
Use [reduce](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce?v=example) method — barbsan, May 18 '17 at 08:34
Not sure to well understand your demand. You want to count the number of `ClassDef` in your whole array ? Or the number of value that contains `ClassDef` in a single object ? — Zooly, May 18 '17 at 08:35
number of each value of ClassDef for eg i have in this json example" 2 A and 2 B and 3 c " — AbouLkhair, May 18 '17 at 08:37
Oh ok! You must write an example in your question, this isn't easy to understand — Zooly, May 18 '17 at 08:38

Stephane Janicaud · Answer 1 · 2017-05-18T09:03:46.827

Try this to find how many times

ClassDef equals C
ClassDef equals C or B

var arr=[{ItemCode:"200500303800356",LastCost:8,OnHand:593889,InventoryValue:4751112,PercOfTotalInventory:18.294517,CumerativePercTotal:18.29,ClassDef:"A"},{ItemCode:"201600701800197",LastCost:400,OnHand:300,InventoryValue:12e4,PercOfTotalInventory:.462069,CumerativePercTotal:75.68,ClassDef:"A"},{ItemCode:"200701507000107",LastCost:75,OnHand:239,InventoryValue:17925,PercOfTotalInventory:.069022,CumerativePercTotal:91.75,ClassDef:"B"},{ItemCode:"200501303400308",LastCost:3515,OnHand:5,InventoryValue:17575,PercOfTotalInventory:.067674,CumerativePercTotal:91.81,ClassDef:"B"},{ItemCode:"200200106701035",LastCost:80,OnHand:27,InventoryValue:2160,PercOfTotalInventory:.008317,CumerativePercTotal:99.28,ClassDef:"C"},{ItemCode:"200200902700248",LastCost:10,OnHand:213,InventoryValue:2130,PercOfTotalInventory:.008202,CumerativePercTotal:99.29,ClassDef:"C"},{ItemCode:"200601302001093",LastCost:.3,OnHand:6,InventoryValue:1.8,PercOfTotalInventory:7e-6,CumerativePercTotal:100,ClassDef:"C"}];

function countOccurences(name, value) {
  var count = 0;
  // If name and values are defined
  if (name && value) {
    // Check either a single value or an array of values
    var values = (value instanceof Array ? value : [value])
    // For each object in array
    arr.forEach(function(v) {
      // If values array contains object[name] value
      if (v[name] && values.indexOf(v[name]) !== -1) {
        // Increment counter
        count++;
      }
    });
  }
  return count;
}

console.log("ClassDef === 'C' :", countOccurences("ClassDef", "C"));
console.log("ClassDef === 'C' or 'B' :", countOccurences("ClassDef", ["C", "B"]));

score 1 · Answer 2 · answered May 18 '17 at 08:40

Through some clever use of .reduce() and Set this is a piece of cake.

const objArray = [{
    "ItemCode": "200500303800356",
    "LastCost": 8,
    "OnHand": 593889,
    "InventoryValue": 4751112,
    "PercOfTotalInventory": 18.294517,
    "CumerativePercTotal": 18.29,
    "ClassDef": "A"
}, ...];

const classDefSet = objArray.reduce((set, obj) => {
    set.add(obj.ClassDef); // add value to the set. If it already exists nothing will happen
    return set;
}, new Set());

const count = [...classDefSet].length; // convert set to plain array
console.log(count); // 3

score 1 · Accepted Answer · answered May 18 '17 at 08:40

You could use an object for the result and use ClassDef as key.

var data = [{ ItemCode: "200500303800356", LastCost: 8, OnHand: 593889, InventoryValue: 4751112, PercOfTotalInventory: 18.294517, CumerativePercTotal: 18.29, ClassDef: "A" }, { ItemCode: "201600701800197", LastCost: 400, OnHand: 300, InventoryValue: 120000, PercOfTotalInventory: 0.462069, CumerativePercTotal: 75.68, ClassDef: "A" }, { ItemCode: "200701507000107", LastCost: 75, OnHand: 239, InventoryValue: 17925, PercOfTotalInventory: 0.069022, CumerativePercTotal: 91.75, ClassDef: "B" }, { ItemCode: "200501303400308", LastCost: 3515, OnHand: 5, InventoryValue: 17575, PercOfTotalInventory: 0.067674, CumerativePercTotal: 91.81, ClassDef: "B" }, { ItemCode: "200200106701035", LastCost: 80, OnHand: 27, InventoryValue: 2160, PercOfTotalInventory: 0.008317, CumerativePercTotal: 99.28, ClassDef: "C" }, { ItemCode: "200200902700248", LastCost: 10, OnHand: 213, InventoryValue: 2130, PercOfTotalInventory: 0.008202, CumerativePercTotal: 99.29, ClassDef: "C" }, { ItemCode: "200601302001093", LastCost: 0.3, OnHand: 6, InventoryValue: 1.8, PercOfTotalInventory: 0.000007, CumerativePercTotal: 100, ClassDef: "C" }],
    result = data.reduce(function (r, o) {
        r[o.ClassDef] = (r[o.ClassDef] || 0) + 1;
        return r;
    }, Object.create(null));

console.log(result);

score 1 · Answer 4 · answered May 18 '17 at 08:45

Yet another reduce example:

let arr = [{
"ItemCode": "200500303800356",
"LastCost": 8,
"OnHand": 593889,
"InventoryValue": 4751112,
"PercOfTotalInventory": 18.294517,
"CumerativePercTotal": 18.29,
"ClassDef": "A"
}, {
"ItemCode": "201600701800197",
"LastCost": 400,
"OnHand": 300,
"InventoryValue": 120000,
"PercOfTotalInventory": 0.462069,
"CumerativePercTotal": 75.68,
"ClassDef": "A"
 }, {
"ItemCode": "200701507000107",
"LastCost": 75,
"OnHand": 239,
"InventoryValue": 17925,
"PercOfTotalInventory": 0.069022,
"CumerativePercTotal": 91.75,
"ClassDef": "B"
 }, {
"ItemCode": "200501303400308",
"LastCost": 3515,
"OnHand": 5,
"InventoryValue": 17575,
"PercOfTotalInventory": 0.067674,
"CumerativePercTotal": 91.81,
"ClassDef": "B"
 },  {
"ItemCode": "200200106701035",
"LastCost": 80,
"OnHand": 27,
"InventoryValue": 2160,
"PercOfTotalInventory": 0.008317,
"CumerativePercTotal": 99.28,
"ClassDef": "C"
 }, {
"ItemCode": "200200902700248",
"LastCost": 10,
"OnHand": 213,
"InventoryValue": 2130,
"PercOfTotalInventory": 0.008202,
"CumerativePercTotal": 99.29,
"ClassDef": "C"
 },  {
"ItemCode": "200601302001093",
"LastCost": 0.3,
"OnHand": 6,
"InventoryValue": 1.8,
"PercOfTotalInventory": 0.000007,
"CumerativePercTotal": 100,
"ClassDef": "C"
}];

let result = arr.reduce((acc, el)=>{
  if (el.hasOwnProperty("ClassDef")){
    if (!acc.hasOwnProperty(el.ClassDef)){
      acc[el.ClassDef] = 0;
    }
    acc[el.ClassDef]++;
  }
  return acc;
}, {});

console.log(result);

score 0 · Answer 5 · edited May 23 '17 at 11:47

0

This may useful for you. you can count the values assigned to the key "ClassDef" as show here the count of the duplicate value assigned to the same key in JSON array

edited May 23 '17 at 11:47

Community

1
1

answered May 18 '17 at 08:43

Ramana V V K

1,245
15
24

score 0 · Answer 6 · answered May 18 '17 at 09:11

Using your sample json object, try this :

var countArr = [];
for(i = 0; i < obj.length; i++)
{
    var val =  obj[i]["ClassDef"];
    if(countArr[val] != null)
    {
        countArr[val] += 1;
    }
    else
    {
        countArr[val] = 1;
    }

}

this will return you

[A: 2, B: 2, C: 3]

How to count property different values in json object

6 Answers6